Why Groundworks Quotes Vary So Much Between Contractors

Developers, quantity surveyors and project managers often see a wide spread between groundworks returns — sometimes tens of percent on packages that appear to use the same drawings. That spread is rarely explained by “one contractor being expensive.” It usually means the bidders are pricing different assumptions about risk, completeness and programme.

This article explains the commercial reasons quotes diverge, how to read a return without treating the lowest number as automatically correct, and what information closes the gap. For what to gather before inviting prices, see What Information Should You Have Before Requesting a Groundworks Quote?. For cost drivers rather than bid comparison, see Groundworks Cost Breakdown.

Two contractors can receive the same PDF set and still price different packages. One may assume formation is handed over clean and dry; another may include reduced-level dig, temporary drainage and soft spots. One may exclude S278 works; another may include an allowance. One may assume imported fill is suitable; another may price disposal of unsuitable material.

When returns land, the first job is to line up inclusions and exclusions — not to average the numbers. The tendering groundworks packages guide covers how to structure a pack so returns are comparable.

Where GI is thin, incomplete or outdated, contractors price residual ground risk differently. Some add contingency; some qualify heavily; some price optimistically and recover later through variations. That alone can create a large spread on otherwise similar packages.

Better GI does not remove all uncertainty, but it narrows the commercial band. See ground conditions risk explained and ground investigation services.

Constrained urban plots, shared haul routes, limited muck-away windows, crane/piling platforms and temporary works design ownership all move cost. Contractors who have walked the site (or studied access carefully) often price higher than those who assumed open-field logistics.

Temporary works responsibility is a frequent silent variable — covered in depth in contractor design responsibility for groundworks.

Adoptable drainage, attenuation, S104 processes and highway interfaces introduce programme and specification risk that not every bidder prices the same way. Incomplete invert levels, unclear adoption standards or missing authority comments often show up as allowances, exclusions or inflated prelims.

• Private vs adoptable drainage scope
• Attenuation ownership and maintenance assumptions
• Connection points and third-party approvals
• S278 / S38 interfaces sitting inside or outside the package

For a structured tender information list, use the groundworks tender checklist. For early feasibility envelopes rather than bid comparison, the groundworks cost calculator can help frame order-of-magnitude thinking — it is not a substitute for tender returns.

Even when contractors price the same drawings, they may not build the price in the same way. One may price from measured quantities and standard outputs. Another may build a method-led price around plant, supervision, access and programme. A third may rely on subcontract quotes for specialist elements.

Those methods can all be legitimate, but they expose different assumptions. A quantity-led return may look tidy while hiding productivity risk. A method-led return may look higher because it has included temporary works or access constraints that others have ignored.

The client should therefore compare the basis of the estimate as well as the total. Ask what plant is assumed, what outputs are expected, what temporary works are included and which risks have been carried as allowances or exclusions.

Two competent contractors can read the same risk differently. One may have recent local experience that makes the ground or logistics feel manageable. Another may have been hurt by similar conditions and price more cautiously. The difference is not always error; sometimes it is risk appetite.

Risk appetite is affected by workload, cash position, relationship with the client, current plant availability and how badly the contractor wants the job. A contractor with a gap in the programme may price more keenly than one already close to capacity.

This is why a very wide spread of returns should trigger questions rather than instant judgement. The high price may contain risk the others missed, or the low price may contain efficiency the others do not have. Clarification is what separates those possibilities.

The cleanest way to reduce quote variation is to improve the tender pack and clarification process. Scope boundaries, disposal assumptions, access, design responsibility, utility status, temporary works and programme constraints should all be stated clearly enough that bidders are pricing the same job.

During tender, clarifications should be answered consistently and issued to all relevant bidders. If one contractor receives extra information and another does not, the comparison becomes distorted before prices are returned.

After returns are received, the comparison should normalise assumptions. That does not mean forcing every contractor into the same method, but it does mean understanding what each price includes, excludes and assumes.

The healthiest outcome is a narrow band of returns built on the same information, with clear qualifications where risk remains. Wide spreads usually mean the tender pack still contains ambiguity. Closing that ambiguity before award is almost always cheaper than discovering it after excavation starts.